As your child grows they will quickly exceed the manufacturer's recommendations for using a rear-facing infant seat. For children older than 1 year and heavier than around 20lbs (9.1 kilograms) a forward-facing seat becomes suitable. If you have purchased a convertible infant seat, then by following the manufacturer's instructions, you will be able to turn your infant seat around and continue to use it. Alternately, you may choose to purchase a dedicated forward-facing child seat.
A forward-facing seat is best used in the rear of the car, where the seatbelt or LATCH system is used to secure the seat itself and integral restraints are used to secure the child. Although it can be installed in the front of the vehicle if necessary (maybe you're driving a truck with no back seat), this must never be done when a passenger air bag is installed. Some more recent model trucks have on/off switches for the passenger side air bags. If you must travel with a child in the front seat of a truck, and you do have an on/off switch, turn the air bag off.